Gas turbines are widely used in industrial, marine, aircraft and power generation operations. A gas turbine includes a compressor section, a combustion section disposed downstream from the compressor section and a turbine section positioned downstream from the combustion section. The combustion section generally includes multiple combustor cans annularly arranged around an outer casing such as a compressor discharge casing. In particular configurations, each combustor can includes multiple bundled tube or micro-mixer type fuel nozzles which may be annularly arranged around a center fuel nozzle.
Bundled tube or micro-mixer type fuel nozzles generally include a fuel plenum, multiple premix passages which extend through the fuel plenum and multiple premix tubes which extend downstream from the premix passages. More particularly, each premix tube extends downstream from an outlet of a corresponding premix passage.
In operation, fuel is supplied to the fuel plenum and compressed air is directed into each premix passage. The fuel is then injected into the flow of compressed air within each premix passage via one or more fuel ports which provide for fluid communication between the fuel plenum and the corresponding premix passage. The fuel and air premix into a combustible fuel-air mixture as they flow out of the premix passages and downstream through the premix tubes. The combustible mixture flows out of each premix tube and into a combustion chamber where it is burned to produce combustion gases.
Currently, each premix tube is attached to the fuel plenum by first aligning the premix tube with a corresponding premix passage and brazing and/or welding the premix tube to the fuel plenum. While effective, these assembly techniques are very time consuming and complex due in part to the large number of premix tubes being placed in a relatively small area. In addition, current assembly techniques result in the formation of a permanent connection between the premix tubes and the fuel plenum which is not conducive for repair/replacement of a damaged premix tube, particularly a premix tube which is surrounded by other premix tubes, following a combustion interval. Accordingly, a system for seating the premix tubes against the fuel plenum which does not require a rigid connection would be useful.